dm table: add zoned block devices validation

1) Introduce DM_TARGET_ZONED_HM feature flag:

The target drivers currently available will not operate correctly if a
table target maps onto a host-managed zoned block device.

To avoid problems, introduce the new feature flag DM_TARGET_ZONED_HM to
allow a target to explicitly state that it supports host-managed zoned
block devices.  This feature is checked for all targets in a table if
any of the table's block devices are host-managed.

Note that as host-aware zoned block devices are backward compatible with
regular block devices, they can be used by any of the current target
types.  This new feature is thus restricted to host-managed zoned block
devices.

2) Check device area zone alignment:

If a target maps to a zoned block device, check that the device area is
aligned on zone boundaries to avoid problems with REQ_OP_ZONE_RESET
operations (resetting a partially mapped sequential zone would not be
possible).  This also facilitates the processing of zone report with
REQ_OP_ZONE_REPORT bios.

3) Check block devices zone model compatibility

When setting the DM device's queue limits, several possibilities exists
for zoned block devices:
1) The DM target driver may want to expose a different zone model
(e.g. host-managed device emulation or regular block device on top of
host-managed zoned block devices)
2) Expose the underlying zone model of the devices as-is

To allow both cases, the underlying block device zone model must be set
in the target limits in dm_set_device_limits() and the compatibility of
all devices checked similarly to the logical block size alignment.  For
this last check, introduce validate_hardware_zoned_model() to check that
all targets of a table have the same zone model and that the zone size
of the target devices are equal.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer refactored Damien's original work to simplify the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-table.c

@@ -319,6 +319,39 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
 		return 1;
 	}
 
+	/*
+	 * If the target is mapped to zoned block device(s), check
+	 * that the zones are not partially mapped.
+	 */
+	if (bdev_zoned_model(bdev) != BLK_ZONED_NONE) {
+		unsigned int zone_sectors = bdev_zone_sectors(bdev);
+
+		if (start & (zone_sectors - 1)) {
+			DMWARN("%s: start=%llu not aligned to h/w zone size %u of %s",
+			       dm_device_name(ti->table->md),
+			       (unsigned long long)start,
+			       zone_sectors, bdevname(bdev, b));
+			return 1;
+		}
+
+		/*
+		 * Note: The last zone of a zoned block device may be smaller
+		 * than other zones. So for a target mapping the end of a
+		 * zoned block device with such a zone, len would not be zone
+		 * aligned. We do not allow such last smaller zone to be part
+		 * of the mapping here to ensure that mappings with multiple
+		 * devices do not end up with a smaller zone in the middle of
+		 * the sector range.
+		 */
+		if (len & (zone_sectors - 1)) {
+			DMWARN("%s: len=%llu not aligned to h/w zone size %u of %s",
+			       dm_device_name(ti->table->md),
+			       (unsigned long long)len,
+			       zone_sectors, bdevname(bdev, b));
+			return 1;
+		}
+	}
+
 	if (logical_block_size_sectors <= 1)
 		return 0;
 
@@ -456,6 +489,8 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 		       q->limits.alignment_offset,
 		       (unsigned long long) start << SECTOR_SHIFT);
 
+	limits->zoned = blk_queue_zoned_model(q);
+
 	return 0;
 }
 
@@ -1346,6 +1381,88 @@ bool dm_table_has_no_data_devices(struct dm_table *table)
 	return true;
 }
 
+static int device_is_zoned_model(struct dm_target *ti, struct dm_dev *dev,
+				 sector_t start, sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+	enum blk_zoned_model *zoned_model = data;
+
+	return q && blk_queue_zoned_model(q) == *zoned_model;
+}
+
+static bool dm_table_supports_zoned_model(struct dm_table *t,
+					  enum blk_zoned_model zoned_model)
+{
+	struct dm_target *ti;
+	unsigned i;
+
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+
+		if (zoned_model == BLK_ZONED_HM &&
+		    !dm_target_supports_zoned_hm(ti->type))
+			return false;
+
+		if (!ti->type->iterate_devices ||
+		    !ti->type->iterate_devices(ti, device_is_zoned_model, &zoned_model))
+			return false;
+	}
+
+	return true;
+}
+
+static int device_matches_zone_sectors(struct dm_target *ti, struct dm_dev *dev,
+				       sector_t start, sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+	unsigned int *zone_sectors = data;
+
+	return q && blk_queue_zone_sectors(q) == *zone_sectors;
+}
+
+static bool dm_table_matches_zone_sectors(struct dm_table *t,
+					  unsigned int zone_sectors)
+{
+	struct dm_target *ti;
+	unsigned i;
+
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+
+		if (!ti->type->iterate_devices ||
+		    !ti->type->iterate_devices(ti, device_matches_zone_sectors, &zone_sectors))
+			return false;
+	}
+
+	return true;
+}
+
+static int validate_hardware_zoned_model(struct dm_table *table,
+					 enum blk_zoned_model zoned_model,
+					 unsigned int zone_sectors)
+{
+	if (zoned_model == BLK_ZONED_NONE)
+		return 0;
+
+	if (!dm_table_supports_zoned_model(table, zoned_model)) {
+		DMERR("%s: zoned model is not consistent across all devices",
+		      dm_device_name(table->md));
+		return -EINVAL;
+	}
+
+	/* Check zone size validity and compatibility */
+	if (!zone_sectors || !is_power_of_2(zone_sectors))
+		return -EINVAL;
+
+	if (!dm_table_matches_zone_sectors(table, zone_sectors)) {
+		DMERR("%s: zone sectors is not consistent across all devices",
+		      dm_device_name(table->md));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /*
  * Establish the new table's queue_limits and validate them.
  */
@@ -1355,6 +1472,8 @@ int dm_calculate_queue_limits(struct dm_table *table,
 	struct dm_target *ti;
 	struct queue_limits ti_limits;
 	unsigned i;
+	enum blk_zoned_model zoned_model = BLK_ZONED_NONE;
+	unsigned int zone_sectors = 0;
 
 	blk_set_stacking_limits(limits);
 
@@ -1372,6 +1491,15 @@ int dm_calculate_queue_limits(struct dm_table *table,
 		ti->type->iterate_devices(ti, dm_set_device_limits,
 					  &ti_limits);
 
+		if (zoned_model == BLK_ZONED_NONE && ti_limits.zoned != BLK_ZONED_NONE) {
+			/*
+			 * After stacking all limits, validate all devices
+			 * in table support this zoned model and zone sectors.
+			 */
+			zoned_model = ti_limits.zoned;
+			zone_sectors = ti_limits.chunk_sectors;
+		}
+
 		/* Set I/O hints portion of queue limits */
 		if (ti->type->io_hints)
 			ti->type->io_hints(ti, &ti_limits);
@@ -1396,8 +1524,42 @@ int dm_calculate_queue_limits(struct dm_table *table,
 			       dm_device_name(table->md),
 			       (unsigned long long) ti->begin,
 			       (unsigned long long) ti->len);
+
+		/*
+		 * FIXME: this should likely be moved to blk_stack_limits(), would
+		 * also eliminate limits->zoned stacking hack in dm_set_device_limits()
+		 */
+		if (limits->zoned == BLK_ZONED_NONE && ti_limits.zoned != BLK_ZONED_NONE) {
+			/*
+			 * By default, the stacked limits zoned model is set to
+			 * BLK_ZONED_NONE in blk_set_stacking_limits(). Update
+			 * this model using the first target model reported
+			 * that is not BLK_ZONED_NONE. This will be either the
+			 * first target device zoned model or the model reported
+			 * by the target .io_hints.
+			 */
+			limits->zoned = ti_limits.zoned;
+		}
 	}
 
+	/*
+	 * Verify that the zoned model and zone sectors, as determined before
+	 * any .io_hints override, are the same across all devices in the table.
+	 * - this is especially relevant if .io_hints is emulating a disk-managed
+	 *   zoned model (aka BLK_ZONED_NONE) on host-managed zoned block devices.
+	 * BUT...
+	 */
+	if (limits->zoned != BLK_ZONED_NONE) {
+		/*
+		 * ...IF the above limits stacking determined a zoned model
+		 * validate that all of the table's devices conform to it.
+		 */
+		zoned_model = limits->zoned;
+		zone_sectors = limits->chunk_sectors;
+	}
+	if (validate_hardware_zoned_model(table, zoned_model, zone_sectors))
+		return -EINVAL;
+
 	return validate_hardware_logical_block_alignment(table, limits);
 }
 

include/linux/device-mapper.h

@@ -237,6 +237,12 @@ typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio)
 #define DM_TARGET_PASSES_INTEGRITY	0x00000020
 #define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)
 
+/*
+ * Indicates that a target supports host-managed zoned block devices.
+ */
+#define DM_TARGET_ZONED_HM		0x00000040
+#define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)
+
 struct dm_target {
 	struct dm_table *table;
 	struct target_type *type;